In recent years, 3D movies of a binocular disparity type have been rapidly spread, which provide right and left eyes of viewers with different images so that the viewers recognize the three-dimensional effect. Showing 3D movies at theaters and watching 3D movies at home with 3D enabled devices are becoming common.
The 3D enabled devices for watching 3D movies at home usually employ liquid crystal shutter glasses. With the liquid crystal shutter glasses, right and left images are alternately displayed on a display (i.e., frame sequential display). A viewer wears the liquid crystal shutter glasses, which shut images coming into the right or left eye in synchronization with the display of an image. This allows the viewer to recognize the right image with the right eye, and the left image with the left eye. As a result, the viewer perceives the three-dimensional effect created by the binocular disparity between the right and left images.
FIG. 7 illustrates the relationship between time and a display position of a ball in a displayed image, where the right and left images of the scene of the ball crossing a screen as shown in FIG. 6 are filmed in 3D at 60 Hz and alternately provided by frame sequential display at 120 Hz. In general, stereoscopic video images are filmed by synchronizing right and left images. When provided by frame sequential display, the right and left images lag behind each other by 1/120 second. When a human views something moving uniformly like this example, it is known that the line of sight moves so as to follow the motion. In FIG. 7, the line of sight follows the displayed ball, and moves along the track of the line of sight. Thus, as shown in FIG. 7, at the time when a one-eye image is displayed, the line of sight from the other eye lags by 0.5 frame in accordance with the direction in which an object moves.
For example, as shown in FIG. 8, when the scene of a ball moving in a longitudinal direction is filmed in 3D and provided by frame sequential display, the lines of sight from right and left eyes lag behind each other in the longitudinal direction by the degree corresponding to the movement of the object for 0.5 frame. The lag between the lines of sight from right and left eyes in the vertical direction may influence ease of viewing the stereoscopic video image, thereby causing eyestrain. For another example, as shown in FIG. 9, when the scene of a ball moving in a lateral direction is filmed in 3D and provided by frame sequential display, the lines of sight from right and left eyes lag behind each other in the lateral direction by the degree corresponding to the movement of the object for 0.5 frame. The lag between the lines of sight from right and left eyes in the horizontal direction may influence the 3D effect of the stereoscopic video image. For example, the lag between the lines of sight from right and left eyes in the horizontal direction may result in perceiving the image closer or further away than the actual location of the image.
As a result, the lag between the lines of sight from right and left eyes in horizontal and vertical directions can reduce the quality of display of stereoscopic images. Therefore, there is a need for a stereoscopic video processing system capable of improving the quality of display of stereoscopic images.